Up to 4 hours before serving, mix pomegranate seeds, onion, lime juice, jalapeño, and garlic; gently fold in avocado. If holding more than 30 minutes, put plastic wrap against the surface of the salsa, then tightly cover; store in the refrigerator. Remove about 30 minutes before serving.

Separate the romaine leaves; wash, then dry thoroughly. Reserve 4 of the most attractive for garnish. Slice the remaining leaves crosswise in thin shreds; reserve.

To prepare the salmon, rub a generous teaspoon of the reserved seasoning mixture over each piece. Arrange the salmon on a baking sheet, skin-side down. Roast at 500 degrees F about 11 minutes for medium rare (salmon should be spongy when pressed with a finger at its thickest part) and 13 minutes for medium-well (salmon should be just firm when pressed with a finger at its thickest part).

While the salmon cooks, mound 1/4 of the shredded romaine on each of 4 serving plates. Top with 1/2 cup salsa. When salmon is done let it cool slightly; it should be warm but not hot. Put a piece of salmon on each plate; garnish each with a reserved romaine leaf and 2 lime wedges.